Too many garden hedges have been planted with Leyllandii or Lawson Cypress, these are the soft leaved conifers that loom over gardens, that seem to be causing so much neighbourly acrimony and court cases, mainly because they grow so tall they block light to peoples gardens or even worse spoil the view that people are used to. When I have asked people why they planted them to a man they say "it's because it gives me an instant hedge" no one says "it's because I like them" but the trouble with conifer hedges are many -
Always grow a mixed hedge, this way you have variety and your hedge will be healthier. You can choose plants that never grow higher than waist height, head height or even small trees that will only grow at most to about 10-12ft it's all down to how and when you cut it in how you achieve the appearance you want. I would suggest getting a book on garden hedges (the local library usually has a good selection of books). Planting Ivy amongst your hedge fills out the bottom half and greatly encourages beneficial wildlife such as predator Beatles that help keep down Aphids and other unsightly pests. Fuschias can be grown into low hedges where they will give a spectacular show of flowers and edible berries (ideal if you have big trees with good side light). Another interesting favourite of mine is the Strawberry tree (arbutus unedo) grown as a hedge it becomes quite dense and develops marble sized red fruit which are edible, it's also evergreen and slow growing.